Protein S Antigen, Free : 10170

Test Code
PROTSF or 10170

CPT Codes

Draw blood in light blue-top tube containing 3.2% sodium citrate. Mix gently by inverting 3-4 times. Centrifuge 15 minutes at 1500 g within 1 hour of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Centrifuge a second time and transfer platelet-poor plasma into a new plastic vial. Freeze immediately and ship on dry ice.

Transport Container
Preferred Specimen
1 mL frozen plasma collected in a 3.2% sodium citrated (light blue-top) tube

Minimum Volume
0.5 mL

Transport Temperature

Specimen Stability
Room temperature: Unacceptable; Refrigerated: Unaccceptable; Frozen: 30 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Received room temperature, Received refrigerated


Setup Schedule
Tuesday & Thursday

Report Available
1-6 days

Reference Range
Male         57-171 % normal
Female    50-147 % normal

Clinical Significance
Total Protein S is comprised of Free Protein S and Protein S bound to a complement protein, C4B-BP.  The relative proportions of the free and bound forms are 40% and 60%, respectively.  It is the free form of Protein S that serves as the cofactor for activated protein C (APC).  The APC/free PS complex serves to down regulate thrombin generation via proteolytic inactivation of Factors Va and VIIIa.  Therefore, a deficiency in Protein S increases an individual’s risk for thrombosis since the normal mechanism of thrombin inhibition is decreased.  Deficiencies of Protein S may be inherited or acquired.  Acquired deficiencies of Protein S result from liver disease, warfarin therapy, nephrotic syndrome, oral contraceptives, L-asparaginase treatment and pregnancy.  
Inherited deficiencies of Protein S are classified into three groups:
-Type I deficiencies correspond to reduced antigen levels of both Total and Free Protein S.
-Type II deficiencies are characterized by a reduced Protein S Activity but with normal antigen levels of both Total and Free Protein S.
-Type III deficiencies are defined by a reduced antigen level and activity of Free Protein S but the antigen level of Total Protein S remains normal.  
Classification of inherited protein S deficiency requires both activity and antigenic testing for protein S.   

Performing Laboratory
med fusion

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.